Update intro to 2D page for 4.4

[skyace65]

• Updates some of the images since the toolbar has changed and there's the new "Game" workspace, all images have gone through squoosh compression
• Removed bullet point for project camera override since it was removed
• Reworded the 3D in 2D section. The way it was before was incorrect, you can't just drag and drop a 3D scene under a subviewport and have it work, the demo it links to explains that a script is used to make this work.

[mhilbrunner]

Thanks, merged.